Branched Graphene Nanocapsules for Anode Material of Lithium-Ion Batteries

Abstract

The promising complex structures of graphene nanocapsules with in situ formed graphene sheets (GC-Gs) have been generated by partially peeling the multiwalled graphene capsules (MWGCs) with a small size of ca. 15 nm. The abundant edges and defects on the in situ induced graphene sheets and capsule walls largely favored the lithiation/delithiation reaction and resulted in a high Li-ion storage level. Since the surface area loss of GC-Gs during stacking and aggregation is generally avoided due to the branched structures and the active doping atoms (N, S) can be intercalated into the carbon lattices during sample preparation, the unique GC-Gs possess an excellent reversible capacity of 1373 mAh g–1 at 0.5 A g–1 as anode material in lithium-ion batteries. This value is more than 3 times that of the theoretical capacity of state-of-the-art graphite counterpart, and higher than those of most carbon materials reported to date and even the composites of metal, alloys with carbon materials.